LEU and thorium fuel cycles for the high temperature reactor (once-through and recycle)

Sets of performance parameters, optimised for minimum costs within the bounds of current technical confidence, are presented for each of the four fuel cycle variants mentioned in the title. The overall cost of the HEU once-through system is found to be significantly more expensive than the other three which are similar. Data are presented on fissile material utilisation, on the isotopic composition of discharged fuel, and on fuel cycle costs. Comments are made on technical status, development needs, safety, environmental concerns including the storage and disposal of irradiated fuel, and on characteristics relevant to proliferation control